Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.17.3.2 (xanthine oxidase)
 8,383 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Milk proteins in acid whey were separated into five fractions according to molecular size by gel filtration chromatography. The second peak, P2, contained proteins between approximately 250,000 and 100,000 daltons. Proteins in P2 were concentrated. After separation into albumins and globulins, each protein group was isolated by DEAE chromatography and hydrophobic interaction chromatography, Isolated albumin fractions were a yellow-colored protein of 89,000 daltons, an unidentified protein of 73,000 daltons, a beta-lactoglobulin of 18,300 daltons, and a red-colored protein of 87,000 daltons. Two types of globulin fractions were isolated: 1) a globulin fraction that coagulated in saturated sodium sulfate but did not coagulate when dialyzed against deionized water included a brown-colored protein of 150,000 daltons, and 2) a bovine serum albumin of 67,000 daltons with unidentified 170,000 and 30,000 daltons bands. A true globulin fraction contained a 77,000 dalton unidentified protein with several faint bands. The red-colored protein was identified as lactoferrin and the brown-colored protein as xanthine oxidase (EC 1.2.3.2.). A yellow-colored protein was concluded to be the denatured protein of contaminated lactoperoxidase (EC 1.11.1.7).
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PMID:Isolation of some minor milk proteins, distributed in acid whey from approximately 100,000 to 250,000 daltons of particle size. 337 95

Ischemic-reperfusion lung injury is a factor potentially limiting the usefulness of distant organ procurement for heart-lung transplantation. Toxic oxygen metabolites are considered a major etiologic factor in reperfusion injury. Although oxygen-free radicals may be generated by many mechanisms, we investigated the role of xanthine oxidase in this injury process by using lodoxamide, a xanthine oxidase inhibitor, to inhibit ischemic-reperfusion injury in an isolated rat lung model. Isolated rat lungs were perfused with physiologic salt solution (PSS) osmotically stabilized with Ficoll until circulating blood elements were nondetectable in the pulmonary venous effluent. Lungs were rendered ischemic by interrupting ventilation and perfusion for 2 hr at 37 degrees C. After the ischemic interval, the lungs were reperfused with whole blood and lung injury was determined by measuring the accumulation of 125I-bovine serum albumin in lung parenchyma and alveolar lavage fluid as well as by gravimetric measurements. Lung effluent was collected immediately pre- and postischemia for analysis of uric acid by high-pressure liquid chromatography. Lodoxamide (1 mM) caused significant attenuation of postischemic lung injury. Uric acid levels in the lung effluent confirmed inhibition of xanthine oxidase. Protection from injury was not complete, however, implying that additional mechanisms may contribute to ischemic-reperfusion injury in the lung.
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PMID:Xanthine oxidase inhibition attenuates ischemic-reperfusion lung injury. 337 17

We have suggested that red blood cell proteolytic systems can degrade oxidatively damaged proteins, and that both damage and degradation are independent of lipid peroxidation (Davies, K. J. A., and Goldberg, A. L. (1987) J. Biol. Chem. 262, 8220-8226. These ideas have now been tested in cell-free extracts of rabbit erythrocytes and reticulocytes. Exposure to oxygen radicals or H2O2 increases the degradation of endogenous proteins in cell-free extracts, as in intact cells. Various radical-generating systems (acetaldehyde or xanthine + xanthine oxidase, ascorbic acid + iron, H2O2 + iron) and H2O2 alone enhanced the rates of proteolysis severalfold. Since these extracts were free of membrane lipids, protein damage and degradation must be independent of lipid peroxidation. An antioxidant buffer consisting of HEPES, glycerol, and dithiothreitol inhibited the increased proteolysis by 60-100%. Mannitol caused a 50-80% reduction in proteolysis suggesting that the hydroxyl radical (.OH), or a species with similar reactivity, may be the initiator of protein damage. When casein or bovine serum albumin were exposed to .OH (generated by H2O2 + Fe2+, or COCo radiation) these proteins were degraded up to 50 times faster than untreated proteins during subsequent incubations with red cell extracts. Mannitol inhibited this increase in proteolysis only if present during .OH exposure; mannitol did not affect the degradative system. Although ATP increased the degradation of untreated proteins 4- to 6-fold in reticulocyte extracts, it had little or no effect on the degradation of proteins exposed to .OH. ATP also did not stimulate hydrolysis of .OH-treated proteins in erythrocyte extracts. Leupeptin did not affect the degradative processes in either extract; thus lysosomal or Ca2+-activated thiol proteases were not involved. We propose that red cells contain a soluble, ATP-independent proteolytic pathway which may protect against the accumulation of proteins damaged by .OH or other active oxygen species.
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PMID:Proteins damaged by oxygen radicals are rapidly degraded in extracts of red blood cells. 359 73

By using EPR spectroscopy of spin-labelled bovine serum albumin (BSA), bendazac was shown to prevent the BSA denaturation induced by urea, heat and free radicals produced in the xanthine/xanthine oxidase system. Bendazac did not inhibit the reduction of ferricytochrome c due to the superoxide flux in the above system nor did it possess a significant antioxidant activity on Fe(II) or Fe(III)-induced peroxidation of lecithin liposomes. It is concluded that the scavenger-like activity of bendazac is due to its interaction with protein molecules, rather than free radicals.
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PMID:Mechanism of the scavenger-like activity of bendazac. 367 37

The effects of dapsone on polymorphonuclear leukocyte functions and lymphocyte mitogen-induced transformation were assessed in vitro and in vivo in normal individuals and in newly diagnosed untreated patients with lepromatous leprosy. The effects of dapsone on the cell-free generation of superoxide by the xanthine: xanthine oxidase system and iodination of bovine serum albumin by horseradish peroxidase were also investigated. In normal individuals dapsone mediated stimulation of polymorphonuclear leukocyte migration in vitro and vivo. Dapsone had no effect on postphagocytic hexose monophosphate shunt activity in vivo. Similar effects were found in patients with lepromatous leprosy. Dapsone also decreased the inhibitory activity of serum from patients with lepromatous leprosy on normal polymorphonuclear leukocyte migration in vitro. Progressive loss of serum-mediated inhibition of migration was observed after ingestion of dapsone by the patients. Further experiments showed that stimulation of polymorphonuclear leukocyte motility was related to inhibition of lymphocyte transformation at high concentrations in vitro, but had slight stimulatory activity on phytohemagglutinin-induced transformation in controls and patients in vivo.
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PMID:In vitro and in vivo effects of dapsone on neutrophil and lymphocyte functions in normal individuals and patients with lepromatous leprosy. 626 48

The proteinaceous coat associated with the cytoplasmic side of milk lipid globule membranes (MLGM) was prepared from bovine and caprine milk by removal of membrane material with non-ionic detergent. These coat preparations, which were enriched in two major proteins, a glycoprotein of polypeptide M, 67 000 (butyrophilin) and a non-glycosylated protein of polypeptide Mr 155 000 (xanthine oxidase), contained small amounts of fatty acids which could not be removed by exhaustive extractions with organic solvents. Both butyrophilin and xanthine oxidase of bovine MLGM were excised and eluted from SDS-polyacrylamide gels and were shown to contain 1 to 2 moles of bound fatty acids per mole of protein. Palmitic, stearic and oleic acids were the predominant protein-bound fatty acids, but no specificity for binding of individual fatty acids was observed. The fatty acids were not rendered soluble in organic solvents when the protein preparations were incubated with phospholipases A or C or with trypsin. Treatment with 0.25 M NaOH at 100 degrees C for 1 h or with 1 M hydroxylamine at 4 degrees C for 16 h, however, released virtually all of the fatty acids associated with these proteins. Similar results were obtained with two major proteins, bands 3 and 4.1, or rat erythrocyte plasma membrane. By contrast, skeletal muscle actin and serum albumin had no bound fatty acids that could be released by alkali treatment. These results show that fatty acids are bound to a number of membrane-associated proteins, both glycosylated and unglycosylated, via linkages that resist purification of the proteins on SDS-polyacrylamide gel electrophoresis and are suggestive of covalent attachment of fatty acids to these proteins. The possible involvement of this acylation in processes characterized by local changes of membrane shape and plasticity is discussed.
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PMID:Tight attachment of fatty acids to proteins associated with milk lipid globule membrane. 706 4

The superoxide dismutase mimetic activity of a copper(II) complex with the tetraazamacrocyclic ligand TAAB has been investigated using the xanthin-xanthine oxidase system for generation of superoxide. The complex exhibits 50% inhibition of the 3-(4-iodophenyl)-2-(4-nitrophenyl)-5-phenyltetrazolium chloride (INT) reduction at the concentration of 0.144 mumol.l-1 (pH 7.8, 25 degrees C). The activity survives in the presence of chelators including EDTA and serum albumin. The enzymatic activity of the complex represents about 3% of that of intact Cu2Zn2SOD.
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PMID:Superoxide dismutase mimetic activity of macrocyclic Cu(II)-tetraanhydroaminobenzaldehyde (TAAB) complex. 750 91

High-performance frontal analysis (HPFA) was incorporated in an on-line HPLC system for the study of the enantioselective binding of BOF-4272, a new xanthine oxidase inhibitor, with human, bovine and rat serum albumins. This HPLC system consists of a HPFA column (diol-silica column), an extraction column (C4 column) and a chiral separation column (beta-cyclodextrin immobilized silica column), which were connected in series via two column switching valves. After the direct injection of a solution of 0.5-400 microM racemic BOF-4272 and 550 microM serum albumin onto the HPFA column, BOF-4272 was eluted, under a mild mobile phase condition (phosphate buffer, pH 7.4, ionic strength 0.17), as a zonal peak containing a plateau region. The drug concentration in the plateau region is the same as that for the unbound drug concentration in the sample solution. A given volume of this plateau region was transferred into the extraction column, and subsequently the extracted BOF-4272 was transferred into the chiral separation column to determine the unbound concentration of each enantiomer. The binding between BOF-4272 and the serum albumins was enantioselective and species dependent. The unbound concentration of the (+)-isomer in rat serum albumin solution was 1.04-1.14 times larger than that of the antipode, while the unbound concentration of the (-)-isomer in bovine serum albumin solution was 1.04-1.16 times larger than that of the antipode. The enantioselectivity of the binding between BOF-4272 and human serum albumin was concentration dependent.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Study of the enantioselective binding between BOF-4272 and serum albumins by means of high-performance frontal analysis. 771 72

Bilirubin, biliverdin and their serum albumin complexes were tested as oxyradical scavengers (superoxide generated by the xanthine/xanthine oxidase system and peroxyl radical-trapping antioxidant ability). As superoxide scavengers the free bile pigments showed activities near to that of serum albumin, higher than the water soluble vitamin E analog Trolox and lower than ascorbic acid. The peroxyl radical-trapping antioxidant abilities of the tested bile pigments were much higher than those of the serum albumin and of the same order as their serum albumin complexes. This interaction with peroxyl radicals showed different stoichiometric factors for bilirubin (approximately 2) and biliverdin (approximately 4).
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PMID:The antioxidant role of bile pigments evaluated by chemical tests. 792 30

Reuptake of glutamate in astrocytes, a critical mechanism involved in the maintenance of physiological excitatory amino acid neurotransmission, is inhibited by both arachidonic acid (AA) and reactive oxygen species (ROS), via incompletely defined molecular mechanisms. Because ROS are generated during AA metabolism and AA can be released as a result of ROS-mediated phospholipase A2 activation, it seems likely that their effects on uptake are mediated by a common mechanism. However, here we show that rapid (10-min) uptake inhibitions by AA or by ROS generated by the xanthine plus xanthine oxidase (XO) reaction are selectively abolished by distinct agents; bovine serum albumin (BSA) acts only on AA, whereas the scavenger enzymes superoxide dismutase (SOD) and catalase (CAT) and the disulfide-reducing agent dithiothreitol (DTT) act only on ROS. Moreover, when added together, xanthine/XO and AA decrease uptake in a fully additive manner. In particular, the effect of xanthine/XO is seen also in the presence of maximal AA inhibition. No major signs of cell damage or chemical reaction between AA and radicals accompany their cumulative effects on uptake. Finally, uptake inhibition elicited by AA and xanthine/XO together is attenuated but not blocked by either BSA, DTT, or SOD/CAT individually, whereas it is fully blocked and substantially reversed by a combination of SOD/CAT and BSA or SOD/CAT, DTT, and BSA. Together, these data indicate that AA and ROS act on glial glutamate transport via distinct noninteracting mechanisms. Therefore, they could independently and additively contribute to the impairment of reuptake function, a phenomenon observed in pathological conditions such as ischemia/reperfusion injury.
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PMID:Glutamate uptake is inhibited by arachidonic acid and oxygen radicals via two distinct and additive mechanisms. 796 90


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